So what you're really saying, I think, is that they are vested, unless the prohibition on working currently (i.e., while employed for the first employer) for a second competing employer is enough to prevent vesting, which is a determination based on facts and circumstances, but seems doubtful.
Under 457(f) proposed regs, if the benefit is payable within the short-term deferral period, actually or constructively, it becomes subject to IRC 409A. So if it takes longer than 2-1/2 months after the end of the year in which vested (see above as to substantial questions regarding when vested), you might want to include on W-2 so that "constructively" received. Frankly, I found the proposed regs somewhat confusing on the point of "constructive payment."